1,721,018 research outputs found
Fitorisanamento applicato ai suoli contaminati da metalli pesanti in siti minerari dismessi
No full textReduction of carbon dioxide point sources emissions through accelerated carbonation of alkaline residues
No full textAerobic granular sludge formation in a sequencing batch reactor treating agro-industrial digestate
Full text linkMost of nitrogen emissions can be ascribed to agro-industrial activities. Since digestate produced by fermentation of agro-industrial residues can be difficult to dispose of due to its high ammonium content, advanced technical- and cost-effective technologies must be developed and applied in order to significantly reduce its impact on the environment. In this study, aerobic granules were successfully cultivated in a granular sludge sequencing batch reactor (GSBR) fed with the ammonium-rich (approx. 2500 mg L−1) effluent of a 3-stage anaerobic digester treating agro-industrial residues. The peculiar characteristics of such wastewater required a 2-step operating strategy aimed at the selection of nitrifying biomass (Step 1) and the formation of aerobic granular sludge (Step 2). During Step 1, nitrifying biomass selection was achieved by properly regulating the cycle length: (Formula presented.) removal rates progressively increased from 42 to 109 mgN L−1d−1, and a corresponding increase in (Formula presented.) specific removal rates from 8 to 24 mgN gVSS−1d−1 was also observed. During Step 2, the increase in selective pressures (i.e. minimum settling velocity and volumetric organic loading rate) led to the formation of compact (average diameter, 1.02 ± 0.43 mm) and well-settling granules (SVI5, 28.6 ± 3.8 mL gTSS−1), which were able to remove up to 89 ± 2% of organic matter (as COD), 79 ± 3% of (Formula presented.) and 59 ± 4% of nitrogen (as a sum of (Formula presented.), (Formula presented.) and (Formula presented.)). The 2-step operating strategy played a key role in biomass selection and subsequent granule formation and maintenance in the GSBR, and may be successfully adopted for the treatment of different ammonium-rich wastewaters
Hydrothermal Carbonization of Olive Pomace: Exploring Hydrochar Applications and Environmental Toxicity of Process Waters
No full textThis study explored the potential of HTC for transforming olive pomace into a solid biofuel, while also addressing the need to manage the environmental risks associated with process waters.
HTC tests were carried out at three temperatures (180°C, 200°C, and 220°C) and two reaction times (1 hour and instantaneous, 0 hours) to produce hydrochar and process water. The hydrochars were extensively characterized to assess their physicochemical properties, focusing on their potential for combustion applications through calorific value analysis, thermogravimetric analysis and elemental composition. Additionally, germination tests using cress seeds (Lepidium sativum L.) were performed to evaluate the potential of hydrochar as a soil amendment.
The process waters generated during HTC were analyzed for their toxicity using three bioindicators: cress seed germination, Daphnia magna mobility, and the activity of nitrifying bacteria. These tests provided insights into the environmental impact of the liquid effluents and their suitability for reuse or safe disposal.
Results showed that both temperature and reaction time significantly affected the yield and properties of the hydrochar. Higher temperatures led to a more carbon-rich hydrochar with enhanced calorific properties, making it more suitable for energy recovery. The germination tests demonstrated that hydrochars produced at lower temperatures were more favorable for plant growth. Low concentrations of hydrochar result in longer seedlings and higher germination rates. In contrast, process water toxicity varied with temperature, showing higher inhibitory effects on bioindicators at elevated temperatures.
At low concentrations, these waters can be biologically treated and show potential as an agricultural resource, thanks to their effectiveness as a soil amendment. Proper dilutions can enhance plant germination and growth, with significantly better results than standard irrigation water
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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